Shaykh Saaleh al-Fawzaan said, “If you mention their (i.e. the refuted persons) good qualities (when warning against them), then this means that you have called (the people) to follow them.
Know, do not mention their good qualities. Mention the error they are upon only. You are not entrusted to praise and approve of their actions – you are only entrusted with exposing the error they are upon so that they may repent from it, and so others can beware of it.
It may even be that the error that they are upon wipes away their good deeds if it is kufr or shirk.
It could also be that this error outweighs their good deeds and perhaps it may seem like they are good deeds in your eyes, yet they are not so in the sight of Allah.”
Ref: Al-Ajwibatul-Mufeedah ‘an As’ilatil-Manaahijil-Jadeedah
Side Point: (My words) – Al-Muwaazanah – Is a innovated principle which numerous contemporary salafi scholars have refuted, from these scholars is Shaykh Uthaymeen, Shaykh Bin Baz, Shaykh Albaani, Shaykh Al-Fawzaan, Shaykh Zayd Al-Madkhalee and many others.
Al-Muwaazanah is when a person criticises an innovator and then claims it is obligatory upon him to praise this innovator and mention his good qualities.
Posted by Abdul Kareem Ibn Ozzie